1. Field of the Invention
The present invention relates to an apparatus and process for separating solids, particularly small particulates such as fines from hydrocarbon/water mixtures and in the further separation of hydrocarbon and water.
2. Related Art
Some hydrocarbon streams are contaminated with particulate solids. For example, hydrocarbons recovered in soil reclamation under the super fund proceedings. Other examples of hydrocarbon streams which may be contaminated with particulate solids are those recovered in remediation of drilling muds, spent motor oils and the like. Shale oil and oil sand hydrocarbons may also contain small solid particles.
The solid particles are usually in the range of 0.1 micron up to 20 and are not easily separated by gravity settling but tend to stay suspended in the hydrocarbons.
The present invention provides an apparatus and process for separating particulate solids from hydrocarbon stream in a continuous process by pressure filtration of the liquids and cross flow removal of the separated solids from the filter medium.
Briefly, the present apparatus uses a porous metal pipe sealed inside a non-porous metal pipe which allows the liquids, e.g., hydrocarbons and water to pass from the first pipe in to the second pipe from which they are removed while solids are retained within the first pipe. There is a system pressure which aids in the filtration and a circulating flow which removes the detained solids and preferably recycle a portion of these solids (having greatly reduced liquids content) with fresh feed back to the system.
The cross flow of the circulating flow prevents buildup of the filtered solids. The hydrocarbons are removed from the chamber formed by the outer pipe. If water is present, the hydrocarbons and water are separated in the outer pipe chamber by decanting, for example, with a bottom drain for the water and an upper drain for the hydrocarbons.
The term hydrocarbons as used herein includes other organic compounds such as nitrogen, oxygen, sulfur or metal containing organic compounds frequently associated with hydrocarbons.